twangster...
The banjo effect is so named because it visually resembles
a swinging banjo string. The audio aspect is not relevant
to this nickname, though the phenomena is accompanied by
the popping sound of repetitive discharges.
A fellow named Reinhard created a lexicon for Tesla Coil
message board readers, and defines it there:
"Banjo Effect: A wavy streamer which looks like a swinging
banjo string."
http://www.altair.org/projects/TCterms.txt
The phenomenon is not visible to the naked eye, but is
evidenced in photos with a long exposure. A search in
Google Images turns up some nice photographs that show
the effect:
"banjo effect"
http://images.google.com/images?q=%22banjo+effect%22
One of the best photos I found is on Tomi T. Salo's website:
http://ttsalo.iki.fi/~ttsalo/tesla/mk2pics/20040214-3067cb.html
The page from which that image was taken also has an
explanation of the phenomenon:
"The closeups show the "banjo effect" quite well. It
happens because the traditional tesla coil with a spark
gap operates with momentary (sort of) bangs - the
primary capacitor charges until the spark gap starts
to conduct and closes the primary resonance circuit.
The energy transfers from the primary resonance circuit
to the secondary resonance circuit, where it creates a
voltage maximum in the topload capacitor (toroid) and
hopefully breaks out in a spark, in which it eventually
dissipates the energy, creating the spectacular light,
sound and heat (and ozone) effect known as the streamer.
The whole process repeats hundreds of times per second,
and since the heated air rises during the off-time, the
new spark forms somewhat above the first..."
More images and discussion on the page:
http://ttsalo.iki.fi/~ttsalo/tesla/mk2pics/
A shorter statement which says the same thing can be
found on the Museum of Electricity's page, here:
"The repeating bands in the discharge have been nicknamed
the "Banjo Effect". They are not visible to the naked eye
since they repeat too fast, however a long camera exposure
shows them clearly. They are caused by the tank circuit's
spark gap repeatedly firing, and graphically illustrate
the pulsed nature of a disruptive Tesla coil."
http://www.electricmuseum.com/exhibits/tesla/coilarchive.shtml
Gary Lau describes it similarly on this page:
The Banjo Effect "...demonstrates that what appears to the
eye as a continuous, luminous streamer, is actually a series
of separate, short-lived arcs that all follow a similar path.
[or channel]
The channel shifts upwards due to it's high temperature. Each
short-lived arc is due to one 'primary bang', or primary
capacitor dumping it's charge."
http://users.rcn.com/laushaus/tesla/sparks.htm
Peter Terren describes it quite succinctly on this page from
his award-winning site:
"...multiple sparks going down the initial ionised path of each
main strike (banjo effect)"
http://members.iinet.net.au/~pterren/tesla_coil_sparks.htm
This image from that page demonstrates how wind can cause
an exaggeration of the banjo effect:
http://members.iinet.net.au/~pterren/T6_windy.JPG
There are multiple images of the effect available on the
other sites mentioned, as well.
Please do not rate this answer until you are satisfied that
the answer cannot be improved upon by way of a dialog
established through the "Request for Clarification" process.
A user's guide on this topic is on skermit-ga's site, here:
http://www.christopherwu.net/google_answers/answer_guide.html#how_clarify
sublime1-ga
Additional information may be found from an exploration of
the links resulting from the Google searches outlined below.
Searches done, via Google:
"banjo effect" "tesla coil"
://www.google.com/search?q=%22banjo+effect%22+%22tesla+coil%22
Searches done, via Google Images:
"banjo effect"
http://images.google.com/images?q=%22banjo+effect%22 |
